1. Field of the Invention
The present invention relates to a thyristor having controllable short circuits, and more particularly to such a device which contains an outer emitter layer of one conductivity carrying an electrode, an outer emitter of the opposite conductivity carrying an electrode, and two base layers respectively adjacent thereto and therebetween, with at least one emitter short circuit located at the edge of the first-mentioned emitter layer and designed as a metal-insulator-semiconductor (MIS) structure, the emitter short circuit consisting of a semiconductor region inserted in the first-mentioned emitter layer and doped opposite thereto and extending up to the boundary surface of the semiconductor body and conductively connected to the first-mentioned electrode, and further consisting of a zone of the base layer adjacent that emitter layer and of an intermediate layer which is formed by a portion of that emitter layer and is covered by a gate electrode carried on insulation, the thyristor having a trigger electrode applied to a base layer, and to a method for the operation of such a device.
2. Description of the Prior Art
Thyristors of the type generally set forth above are disclosed in the German patent application Nos. P 29 35 366.5 and P 29 45 324.5. When the controllable emitter short circuits are designed as depletion type MIS structures, then, without the supply of a control votlage to their gate electrodes, they respectively close a short circuit path which bridges the pn junction between the emitter layer connected to the cathode (anode) and the adjacent base layer. Therefore, the thyristor exhibits good stability, i.e. higher security against unintentional trigger operations upon occurrence of voltages at the anode/cathode elements which are poled in the forward conducting direction, the voltages sometimes rising very quickly (high dU/dt load). If the thyristor is triggered by a current pulse supplied to its trigger electrode, then a trigger voltage pulse which can be tapped at the trigger electrode can be applied to the gate electrodes of the controlled emitter short circuits so that the same are suppressed for the duration of triggering. The suppression represents a turn-on measure and results in the fact that a fast, controlled triggering occurs over the entire thyristor cross section. If, on the other hand, controllable emitter short circuits are designed as enhancement type MIS structures, then the same are inoperative without the supply of a control voltage to their gate electrodes and are only switched on by a control voltage pulse which exhibits the opposite polarity of the trigger voltage pulse and for the duration of the control voltage pulse. Such a control occurs in the current-conducting state of the thyristor for the purpose of achieving a fast blocking of the thyristor, and thus represents a turn-off measure.